This application would enable me to move from part-time research and part-time administration to full-time research in psychiatric epidemiology. The proposed research had methodological and substantive components and is an extension of my work in the Epidemiologic Catchment Area (ECA) survey and other research I have been involved with over the past several years. The research has three long-term goals: 1) To examine the predictive validity of psychiatric diagnoses based on non-clinician (lay) interviewer data, to compare this to the predictive validity of clinician diagnoses, and to assess the implications of the results of this comparison for epidemiologic studies. 2) To examine the natural history of psychiatric disorder in subjects ascertained in the general population using diagnosic criteria which have been developed through the study of subjects ascertained in clinical settings and to assess the implications of these results for population studies. 3) To further the development of uniform methods of case identification in clinical and epidemiologic research. Four specific projects are outlined. The work entails collaborative efforts with other investigators in the United States, in the United Kingdom, and at the World Health Organization.